Improved mode op producing white lead



' Letters Patent No. 97,365, dated Noe-ember 30, 1869.

turnover: MODE or rnonvcrne WHITE Leena i The Schedule referred to inthese Letters Patent and making part of the same Ta all whom it onlyconcern:

Beit known .thatwe, Jonxfisumronn 1).-\ on and EDWARD MILNER, ofWornington, in the county of Lancaster, England, have iuventedzi new anduseful Improved Method of Producing White Pigmen-ts from Lead; and we dohereby declare that the following is a full and iexact descriptionthereof.

ur invention relates to animproved method of the changeof the leadbodies into carbonates is coinplete. The paste is now-well \vnshedwithwater, and the supernatant liquid, which contains monoom-bonare of soda,is separated from the white lendby tilt-ration, and boiled down todryness, and disposed of as soda-ash, or it nniy be crystallized, or maylie again converted into bicarbonate of soda by treatment with carbonic:icid, and used to convert further qunntities otlend oxides, 850., intocarbonates. instead ot'grinding, the lead oxides, &o., in n fine'shiteof division,-

' may simply be mixed with bionrbondte of soda, and

Water, and "left to themselves, when the conversion into carbonates goeson in the some manner, only much more slowly.

Pecondly, We mix litlmrge, hydrated oxides of lead, or basicsnltsof-lead, wit-h caustic soda, monoeerboimte of soda, or acidcarbonates of soda, and sntiioient wnter to form a st-ifiish paste. Themixture is no in- .liqnid treatedns before described.

t-roduced into-a suitable closed mill, and during the grinding a, streamof carbonic-acid gas is passed into it. After conversion of thelendbodies intocarbo nates, they are \vas'hedwith waiter, :ind thesupernatant In carrying out our process by this secondly-describedmethod, we'do not ,bind ourselves to any particuler proportion of leadoxides and soda, but may saytiles-equivalents of each answer very well..'1"hequantity of the soda-salts may, howevor, he reduced with-advantageif found desirable. I

Grinding may also be dispensed with by mixing the lead oxides, 810., inafine state of dii-ision, with the caustic soda, monocarbrmate, ornoid'cm'boiu tes of soda, as described, andexposing the mixture in asuitoble room to the act-ion ofenrhonie acid. i

We may say that artificial heat accelerates the1conversion both in thefirst and secondly-deseiibed operetions, but is not essential to theirsuccess.

We claim the m ennfiietureotonrbonhte of lead, by the notion of acidcarbonates of' the alknlies on litharge, by drated oxides of lead, andinsoluble bnsio szilts=-pt'lozul, either by direct addition, asdesrribml in our first part, or indirectly by the mixture of the lendoxides, &c., .with the caustic tilkalies or theirmonocnrbonate or acidsalt-s, and theirconversion into bienrbonutes during, the time they arein, contact with thelithnrgc, hydrated oxides, or insoluble bnsic saltsof loud.

Done at Manchester, England, this 29th day of September, A. 'l'). 1869.v

' JOHN GALLEMORE Il).\ Ll). EDWAlll 4 .\-l ILNER.

\Yitnesses:

(l. .l. lireuns, Patent Ayn",

-259 Black Friars Street, Manchester. V (l, Snr'rmus Hnmris,.1atmtAgent,

39 Black Friars Street, mwlu'stcr.

-vionx :GALLEMORE DALE AND E WARD LMILNEI}, or, WARRIN'e-roN,

ENGLAND.

